(1.) Field of the Invention
The present invention relates to a synchronous system for a three-stage ball bearing slide, and more particularly, to a mobile track when pulled to extend drives a carrier track to slide synchronously and is temporarily positioned at its terminal without being retracted thus to permit the carrier track to be directly subject to the push thereon to once again be retracted into a fixed track.
(2.) Description of the Prior Art
A conventional three-stage ball bearing slide usually contains a fixed track (outer track), a carrier track (middle track), and a mobile track (inner track). Taking the ball bearing slide adapted to a cabinet and its drawers for example, the fixed track (outer track) is fixed to the cabinet, the mobile track (the inner track) is each fixed to both sides of the drawer, and the carrier track (middle track) is inserted into the fixed track (outer track) by means of a slide aid, usually a ball bearing, to slide and carry the mobile track (inner track), thus to make the mobile track (inner track) and the carrier track (the middle track) engaging in reciprocal movement along the same axial direction in relation to the fixed track (outer track) for the drawer to be pulled out or in against the cabinet. The three-stage ball bearing slide of the prior as illustrated in FIG. 13 of the accompanying drawings defines the track according to its location. Slide aids D, E are respectively provided between the inner track (A) and the middle track (B) as well as between the middle track (B) and the outer track (C). A retainer (F) and a compressor (G) are respectively provided in the inner track (A) and the middle track (B) to allow one-way positioning when the inner track (A) is pulled out to its extreme and to pull the retainer (F) to release it from the compressor (G) for the inner track (A) to disengage from the middle track (B).
So far the development of the design of those ball bearing slides adapted to cabinets and drawers has been focusing on two purposes, to hold the carrier track (middle track) in positioning when pulled to its fully extended location, and to be pulled for movement synchronously with the mobile track (inner track). Design of the linking mechanism associated with those two purposes may be referred to U.S. Pat. Nos. 5,551,775 and 5,757,109; US Published Application Nos. 2002/0057042, 2003/0080659, 2003/0107309, and 2003/0111942; and Taiwan Utility Model Patent Nos. 215789 and 197034 (No. 197034 same as that of US Published Application No. 2003/0178922 owned by this Applicant).